Grandstand Star Force Capacitor Replacement Guide
The electrolytic capacitors on the main board of the Grandstand Star Force, Epoch's 1984 space game sold in the UK by Grandstand.[1] No parts list, schematic or written repair has been published for Star Force, its Epoch original or the Yeno Super Galaxy II, which a collector identifies as the same game.[2] Two repair videos show the inside: retro_restos's teardown of 2023 and Repairing Faulty Tech's repair of 2025. Their narration could not be retrieved, so what follows comes from frames of those videos looked at at full size, and the capacitor values could not be read in any of them.[3][4] Below are where the capacitors are, what is known of the circuit around them, and how to read and record them on your own board. Faults that are not capacitors are on Grandstand Star Force Troubleshooting Guide; general signs of a failing capacitor are on Capacitor Failure Symptoms.
What the capacitors do on this board
[edit | edit source]Star Force runs from four C cells or a mains adaptor set to negative polarity, a nominal 6 V.[5] Its microcontroller is an NEC D7528C, read as D7528C-016 by the Handheld Museum.[1] The main board, marked 96291 with an Epoch logo, carries the display tube (silkscreen V01: FIP10AM33T) and, along the edge beyond the tube, a round TDK transformer, small transistors and the electrolytic capacitors.[3][4]
Nobody has traced the Star Force's circuit. On the Firefox F-7, whose microcontroller is from the same NEC family, an owner's schematic shows a power transistor driving a small transformer whose windings are rectified and smoothed by the electrolytics into the display and chip supplies, with one large electrolytic across the 6 V input.[6] Whether Star Force's supply is built the same way has not been shown; the parts visible along the board edge are of the same kinds.[3]
Capacitor list
[edit | edit source]Positions are given with the board as retro_restos shows it in the base of the game: the tube lying across the board, the ribbon cable to the control board at the bottom left, and the transformer at the top edge.[3]
| Ref | Where it is | What is visible | Value | Voltage | Source |
|---|---|---|---|---|---|
| C03 | Top edge, right of the transformer, beside diode S06 and a ceramic disc | Black radial, standing | Not legible | Not legible | [3] |
| Designator hidden | Top edge, left of the transformer, beside two small transistors | Small radial with a light-coloured top, standing | Not legible | Not legible | [3] |
| Designator hidden | Top left corner | Larger black radial, standing | Not legible | Not legible | [3] |
The tube covers most of the component side, so the board may carry more electrolytics than the three that can be seen. No value or voltage has been published for any of them.[3]
Failure signs on Star Force
[edit | edit source]No published repair of a Star Force has traced a fault to a capacitor:
- retro_restos's game was grubby, with an intermittent power socket, a broken screen mount and unresponsive controls; the video works through those faults.[3]
- Repairing Faulty Tech's game would not power on. He worked on it alongside a second Star Force, and an on-screen caption at about 10:04 reads "Transformer from working unit into original unit"; the video's narration, which would say what the fault was, could not be retrieved.[4]
If a Star Force has sound but a dark or dim display, or is dead with good cells, check the DC socket and its battery contact first, then look for leaking or bulging electrolytics and measure them out of circuit.[3] See Grandstand Star Force Troubleshooting Guide.
Reading and recording your own board
[edit | edit source]Nothing has been published, so record your own board before ordering parts.
- Photograph the main board square on before you remove anything, including the edge beyond the tube. Note the white label number (0040731 on retro_restos's board) and the board number, 96291.[3]
- For each electrolytic, write down its C number, the value and voltage printed on its sleeve, its maker, its diameter and height, and which way its stripe faces.
- Look under the tube with a torch for any electrolytics hidden there.
- Read the transformer's marking and the microcontroller's full marking (the Handheld Museum gives D7528C-016).[1]
- Measure each capacitor once it is out; a meter that reads capacitance and ESR will show a dried-out part.
Replacement procedure
[edit | edit source]These steps follow what retro_restos's video shows; its narration could not be checked.[3]
- Take out the four C cells. The battery box is in the underside of the base, with the cells in two rows.[5][3]
- Undo the screws in the underside of the base (retro_restos reaches them at about 7:14) and lift the silver top, with its screen window, up and off the base (7:20-7:38).[3]
- A purple filter sheet lies over the tube and lifts away (11:30-12:15). The screen window and its lens can be taken out of the top for cleaning but need not be for a recap.[3]
- The control panel is held by screws (13:30-14:15); under it is the green control board, joined to the main board by a ribbon cable. Keep the ribbon flexed as little as possible.[3]
- The main board lies in the base with the tube on it. Work on the capacitors from the edge beyond the tube, keeping the soldering iron off the glass.[3]
- Note each capacitor's polarity, then remove it and read its value. Fit a new radial electrolytic of the same capacitance and the same or a higher voltage, the right way round, and no taller than the original so that the top still fits.
- Refit the control panel, the filter sheet and the top, and refit the base screws.
More on the case, cells and DC socket is on Grandstand Star Force General Maintenance.
After the work
[edit | edit source]| Check | Expected | Source |
|---|---|---|
| At switch-on | An electronic melody plays and the display lights, with "L1" at the top | [5] |
| Skill and phase | The skill button steps through four levels and the phase button through seven phases | [5] |
| START | Sounds and shows the number of lives | [5] |
| SOUND off | The game plays in silence | [5] |
No supply voltages or currents have been published for this game.
Related pages
[edit | edit source]- Grandstand Star Force
- Grandstand Star Force General Maintenance
- Grandstand Star Force Troubleshooting Guide
- Grandstand Firefox F-7 Capacitor Replacement Guide: the Epoch game with a microcontroller from the same NEC family, whose capacitors are known
- Capacitor Failure Symptoms
- Battery Explosion, Capacitor or Corrosion Damage
References
[edit | edit source]- ↑ 1.0 1.1 1.2 Handheld Museum, "Grandstand Star Force" (retrieved 2026-10-18): 1984, VFD, four C cells, model 11055, "CPU: NEC D7528C-016"; Grandstand release of Epoch's Star Force.
- ↑ Handheld Museum forum, "Epoch Star Force", 2012-2019 (retrieved 2026-10-18): a member notes that the uncommon Yeno Super Galaxy II is "the same as Epoch and Grandstand's Star Force".
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.14 3.15 3.16 retro_restos, "Vintage Electronic Grandstand Star Force Teardown & Repair. Broken Screen, Power Fix & Bad Joystick", YouTube, 21 June 2023 (description read 2026-10-18; narration not retrievable; frames looked at 2026-10-19, overview at 360p and 19:50-20:30 at 1080p). Description: "a rare opportunity to see inside the Star Force game"; the game was grubby, with an intermittent power socket, a broken screen mount and unresponsive controls. Frames: the battery box under the base, cells in two rows (2:32); a screwdriver at the screws in the underside (7:14) and the silver top lifted off the base (7:20-7:38); a purple filter sheet over the tube (7:38, removed 11:30-12:15); the screen window and lens taken out of the top (10:00-11:15); the control panel unscrewed (13:30-14:15) over a green control board with a ribbon cable to the main board; the main board in the base marked 96291 with an Epoch logo, label 0040731, silkscreen V01: FIP10AM33T under the tube, and along the far edge a round TDK transformer, two small transistors, a ceramic disc, diode S06 and three standing electrolytics: C03 (black) right of the transformer, a small one with a light-coloured top left of it, and a larger black one in the corner, none with a legible marking (19:50-20:30).
- ↑ 4.0 4.1 4.2 Repairing Faulty Tech, "Grandstand STAR FORCE 80's game won't power on - Can I fix it?", YouTube, 13 April 2025 (description read 2026-10-18; narration not retrievable; frames looked at 2026-10-19). A Star Force that would not power on, worked on alongside a second Star Force. Both main boards are marked 96291 (on the solder side and the component side). Burned-in captions: "Earlier...." (about 9:52) and "Transformer from working unit into original unit" (about 10:04), over frames of a board being worked on with a soldering iron.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Grandstand, Star Force instruction booklet (distributed by Adam Imports Ltd, Harrogate; printed in Japan), hosted here as File:Grandstand Star Force Instructions.pdf. p. 1: four Duracell MN1400 cells, or the Grandstand Universal Mains Adaptor with its polarity switch set to negative; at switch-on an electronic melody plays and the display lights; the game is set to skill level 1 ("L1" at the top of the display) and phase 1; with the sound switch off the game plays without sound effects; START sounds and shows the number of lives. p. 2: four skill levels and seven phases, chosen with the skill level and phase select buttons.
- ↑ Philip Bryden, "Grandstand Firefox F7" schematic, "Power rail" sheet, KiCad 6, revision 1, 8 June 2022, PDF on MEGA (retrieved 2026-10-18). For the Firefox F-7: the D882 power transistor S04, driven by S03 (C945), drives the ten-pin transformer TX-30; diodes S05 to S12 rectify its windings; electrolytic C01 lies across the 6 V input and C02 to C04 on the rectified rails.